In manufacture of electronic devices, a metallic material may be buried in a recess formed in an insulation film. For example, wiring is formed by burying the metallic material in a contact hole or a trench. A reflow technology has been known as an example of a process for burying the metallic material.
In the reflow technology, a film of a metallic material is formed on a surface of an insulation film having a recess. Thereafter, an object to be processed, which has the film of the metallic material, is heated. Thus, the recesses are filled with the metallic material, which becomes fluidified in this way.
In a conventional reflow technology, a barrier layer is formed on an insulation film, a seed layer containing copper is formed on the barrier layer, and a fixed layer is formed on the seed layer. The fixed layer is formed with materials such as Ta, Ti, W, Ni, Ru and Mn, oxides of these materials or nitrides of these materials. When an object to be processed is heated, the seed layer and the fixed layer become fluidified, and a recess is filled with the fluidified material. This technology suppresses generation of cavities, such as voids, in the recess, using the fixed layer.
There is a need in some circumstances to use cobalt as a material to be buried in a recess formed in an insulation film. However, if the reflow technology is applied to a cobalt film, the cobalt may accumulate preventing the fluidified cobalt from flowing toward the recess.
Therefore, it is necessary to supply cobalt to a recess formed in an insulation film while suppressing the generation of cavities.